This invention relates to a wheeled carriage for supporting a patient in a substantially horizontal position and, more particularly, to an auxiliary wheel arrangement for facilitating the raising of an auxiliary wheel away from a floor surface and the lowering of the auxiliary wheel onto the floor surface to assist the castered wheels in moving of the carriage.
Wheeled carriages for supporting a patient in a substantially horizontal position are well known in the art and a representative example of an early version of such a device is illustrated in Dr. Homer H. Stryker""s U.S. Pat. No. 3,304,116, reference to which is incorporated herein. Other of such wheeled carriages are disclosed in U.S. Pat. No. 6,256,812, U.S. patent application Ser. No. 09/489,584 filed Jan. 21, 2000 and U.S. patent application Ser. No. 10/083,234 filed Feb. 26, 2002, all of which are presently owned by the Assignee of record for this invention, and incorporated by reference herein.
U.S. Pat. No. 5,987,671 discloses a stretcher having a retractable auxiliary wheel that is biased into contact with a floor surface by a spring.
U.S. Pat. No. 5,348,326 discloses a carrier with deployable center wheels that are maintained in a retracted position by a spring.
One object of the invention is to provide an auxiliary wheel support bracket that is spring biased by a first spring to pivot about the axis of a shaft into a stowed position, and when deployed, separately spring biased by a second spring and pivotable about the same axis to maintain contact with a floor surface.
Another object of the invention is to provide an auxiliary wheel support bracket, as aforesaid, wherein the first and second springs are in alignment about the axis of the shaft with one spring being located adjacent one end of the shaft.
The objects and purposes of the invention are met by a wheeled carriage for supporting a patient in a substantially horizontal position, which has thereon a patient support having a head end and a foot end and a pair of lateral sides intermediate the head and foot ends, and a wheeled base having a length and supporting the patient support and enabling movement of the patient support. The wheeled base includes at least four floor surface engaging and castered wheels spaced from one another. An auxiliary wheel assembly is secured to said wheeled base and includes a rotatable support shaft with an axis and a stop element mounted to the rotatable support shaft. An auxiliary wheel support bracket has a first end rotatably secured to the support shaft to enable free rotation about the axis thereof and has a stop mounted thereon. An auxiliary wheel support spring continually urges the auxiliary wheel bracket in a first direction about the axis of the support shaft and the stop into engagement with the stop element. An auxiliary wheel is rotatably secured to a second end of the auxiliary wheel support bracket. A deployment apparatus rotates the support shaft and the stop element in the first direction about its axis to move the auxiliary wheel between a stowed position spaced from the floor and a deployed position engaging the floor. In the deployed position, the auxiliary wheel contacts a floor surface and the mass of the wheeled carriage is applied against the auxiliary wheel support spring to separate the stop from the stop element and pivot the auxiliary wheel support bracket about the axis of the support shaft so that each of the castered wheels and the auxiliary wheel maintain contact with the floor surface.